SIOUX FALLS, S.D. — As the National Park Service and Department of Interior move closer to creating the nation’s first national park managed by an American Indian tribe, new details about what the park could look like are being released, including plans to establish a free-roaming bison herd.

The National Park Service and the Interior Department on Thursday released the final version of a plan that would establish the first national tribal park at the South Unit of Badlands National Park, which is entirely within the Pine Ridge Indian Reservation in South Dakota.

Congress must still approve the establishment of the park, but Thursday’s announcement means the National Park Service and the Oglala Sioux tribe can begin implementing parts of the plan and identifying what a tribal national park looks like.

“As we seek to tell a more inclusive story of America, a tribal national park would help celebrate and honor the history and culture of the Oglala Sioux people,” Secretary of the Interior Ken Salazar said in a statement.

The U.S. government’s War Department took what is now the South Unit from the Pine Ridge Indian Reservation to establish a practice bombing range in the 1940s. It was returned to the Oglala Sioux tribe in 1976 and has since been co-managed with the Park Service. The tribe began pushing for greater control of the unit’s 133,300 acres about a decade ago, after they disagreed with the Park Service’s plans for the land.

The plan released Thursday recommends Congress create a new designation for a tribal national park. Depending on Congressional action, it could be administered several different ways, including as a unit of NPS managed by tribal members who work as NPS employees or by tribal members who work for the tribe.

Eric Brunnemann, superintendent of the Badlands National Park, said one goal is to create a free-roaming, economically viable herd of bison at the park as part of the Park Service’s plan to establish and sustain at least three wild bison herds in the central and western United States over the next 100 years.

“We have tried for many years to put buffalo into the South Unit, but because the parcels are so small, you can’t really succeed,” Brunnemann said.

He said officials are working with nongovernmental organizations to test and study the viability of piecing together parcels to allow for a free-roaming herd in the area and working with donors for funding.

“No one wants to go down the path of a good idea if it’s going to unravel,” he said. “We need to have the science and the economics at the table, hand in hand.”

The plan calls for the Park Service and Oglala Sioux tribe to enhance the wildlife habitat and improve roads and trails for visitors in the park.

At least 95 percent of the facilities for visitor use and park management are located in the North Unit, which is connected to Interstate 90 and draws more than 900,000 visitors annually. The South Unit draws around 9,500 visitors, according to the National Park Service.

Oglala Sioux tribal president John Yellow Bird Steele has said he looks forward to the park adding one thing much sought after among reservation residents: jobs.

“For a few of our people, it would be creating careers in archaeology, anthropology, paleontology,” he said.

The tribe recently hired Gerard Baker, the former superintendent of Mount Rushmore National Memorial, as executive director of the Oglala Sioux Parks and Recreation Authority. He has created a new Department of Tourism within the organization and said he has many plans for increasing visitors to the South Unit, including with guided tours, more events and extended hours.